Ink-jet printers are well known in the art, and many utilize a carriage which carries one or more ink-jet cartridges or pens in a traversing or scanning movement transverse to the printer paper path. It is also known to provide an external stationary ink reservoir connected to the scanning cartridge via a tube. The external reservoir is typically known as an "off-axis" ink reservoir. While providing increased ink capacity, these off-axis systems present a number of problems, however. The space requirements for the off-axis reservoirs and tubing impact the size of the printer, with consequent cost increase. Moreover, pressure drops through the tubing can reduce printer throughput and affect printing quality. Another problem is that of vapor losses from the tubing and air diffusion into the tubing system. In the past, tubing such as LDPE (low density polyethylene) has been used, since it is a low modulus material which is easy to bend. This low modulus material suffers from relatively high vapor losses and air diffusion into the tube. As a result of the vapor losses, the ink can change properties, degrading print quality and eventually causing tube or printhead clogging. As a result of air ingestion, the printhead can fill with air. During thermal fluctuations, the air can expand, causing printhead drool. In addition, the air can cause printhead starvation. Further problems include the force exerted on the carriage by the tubing, and the stresses on the tubing that tends to cause buckling or fatigue failures. These problems are exacerbated with a low end off-axis printing system with its relatively small form factor.
It would therefore be an advantage to provide a compact, low end off-axis printing system.
It would further be advantageous to provide such a printing system which permits high throughput printing, with relatively high flow rates through the tubing.
Still other advantages would be provided by an off-axis printing system with high reliability due to low vapor losses and air diffusion, yet with minimal tubing pressure drops while minimizing the force exerted by the tubing on the carriage to maintain accurate printhead alignment.
Only certain components of a printing composition delivery system, such as an off-axis ink delivery system of an ink-jet printer, are actually wetted by the printing composition. Other components are not. Components that are wetted include the printing composition supply station connector which connects to a supply of printing composition, such as a replaceable ink supply cartridge, and the printing member connector which connects to a printing member, such as a print cartridge. Another component that is wetted is conduit, such as one or more ink delivery tubes, which supplies printing composition from the printing composition supply to the printing member. Components that are not wetted include motors and electrical circuitry.
The ability to easily separate the wetted components of the printing composition delivery system from the unwetted ones would be a desirable improvement over the currently known art for several reasons. For example, wetted components of the printing composition delivery system must be leak-tight. Inspection, testing, and servicing of leak-tight components of the printing composition delivery system are simplified if these components are a separable unit from the printing composition delivery system. Additionally, wetted components in actual contact with the printing composition are more likely to be subject to corrosive action of printing composition solvents and may be rendered inoperable due to clogging of dried printing composition under certain long-term environmental conditions. The unwetted components of the printing composition delivery system may have longer life due to a lack of contact with the printing composition. The ability to remove a damaged module wetted by the printing composition and replace it with a new one prevents the need to replace the entire printing composition delivery system, including the undamaged portion or, alternatively, the entire printing device. This ability to replace only a module of the printing composition delivery system thus saves costs. It also increases expected reliability of repair because it eliminates the need for electrical connections to be made to replaced parts which can be fragile and subject to mechanical damage from things such as improper insertion or contamination from debris.
A further advantage of a replaceable module is that it enables use of different incompatible printing compositions in the same printing device by switching components of the printing composition delivery system which are wetted by the printing composition. Without such replacement, incompatible printing compositions could mix in the printing composition delivery system and cause failure or degraded performance of the printing device.